Treatment of hides



' Patented Nova 19, 1929 P A-TENT OFFICE or'ro nbnm, ornanmsrnnci, GERMANY TREATMENT or ninns I '10 Drawing. Application fi led February 5, 1925, Serial- No. 7,145,. and in Germany April 1, 1924.

My invention refers to the treatment of hides, skins, pelts and furs, and more'especially to the preparation ofhides for the tanmng. As is well known to those skilled in the art, the raw or salted hides, in order to rei move the hairs or bristles, are treated with a suitable depilatory, such as lime, which being slightly soluble injwater does not give satis- 1o factory results and requires many daystreatment. It has thereforebeen proposed to unhair the hides by means of sulphides such as sodium sulphide which, however, while allowingofremoving the hairs or bristles in a comparatively short time, at the same time acts on them in such'a manner as to render them unfit for further use.

,It is an object of my invention to provide means whereby the hides are acted upon in suchimanner that the hairs or bristles can -easily be removed after;a short treatment without however being injured and rendered unfit for further use. 4

To this end I subject thehides to a sequence 2 of operations comprising a treatment with ammonia. I am aware that it has been proposed to employ ammonia for instance by Y exposing the hides to the combined action ofammonia and steam, but such treatment has so roved to be ineffective, inasmuch as a'uniorm depilation cannot be obtained.

. According to the present invention the hides, either raw or salted, are first treated with a salt of an alkali forming-metal inthe monia. The term salt of an alkali forming metal, wherever it occurs, is intended to in results-and Imay add the acid to the salt or salt solution at the beginning or at a later a I The operation of rinsing can however also I .be dispensed with, depilation being efi'ected also without removing the salts. This is conrary to the practice generally followed of presence of an acid and thereafterwith am-'.

found that this not thecase and I therefore oftendispense with washing or rinsing whereby much time is saved. 7

Preferably, tryptically active substances, for instance the pancreas enzymes, are caused to act on the hides either before or after tre'atmg with ammonia, in order to effect the bating, to wash out the dirt and to further depilation Without any extra bating procedure. Preferably, an enzyme reparation is em ployed which is obtained y compressing the- 'respectlve tissue (such as for instance the pancreas. gland) with a view to recovering therefrom the llquor containing the enzymes (such aspan'creas enzyme), this liquor being preferably mixed for absorption with a finely 7 subdivided material such as wood meal. The preparations thus obtained 'form dry, and stable products. I may, however, also employ the choplped or otherwise .comminuted glands as suc v .The treatment with ammonia'may be carr ed out by fulling the hides in a watery solut1on of ammonia, part of which can however be'replaced by other'alkaline substances such as soda or potash. I have sometimes .found so it useful to em loy ammonia in the form of.

'a gas and pre erably in statu nascendi by liberating it from a suitable salt capable of 7 developing an easily decomposable ammonia compound or gaseous ammonia. I mayfor instance employ a mixture of a salt of an alkali forming metal such as sodium chloride and an easily decomposable ammonia compound, such as ammonium chloride for the preparatory treatment of the i -hi des,'a suitable acid being added, and the ammonia required fordepila'tion may then be liberated from the ammonia compound by adding a substance such as soda which 1 will decompose the ammonium chloride,- liberating ammonia.

After the hair has been removed, a plumping agent (for instance soda) can be added, and the plumping operation can be followed by a bating operating, a suitable hating agent, for instance pancreas enzymes being added.

Instead of treating the hides with solutions of the salts or other substances, I can also use these substances in solid state, the hide being first treated for instance with a mixture of a salt of an alkali forming metal such as sodium chloride, an ammonia salt such as ammonium chloride and an acid, for instance lactic acid, and thereafter with a mixture of pancreas enzymes and soda, this latter being designed to liberate ammonia from the ammonium chloride.

In carrying out my invention I may for instance proceed as follows Example I 100 kilos salted calfskins are fulled in 200 liters water, 20 kilos sodium chloride and '1 kilo lactic acid. The acidis then neutralized and 1 kilo of a preparation as aforesaid containing pancreas enzymes is added. After the lapse of a few hours, the hides are withdrawn from the bath and the salts are removed by rinsing with water, whereupon they a' perfect depilation, the hairs being rendered v easily removable.

Example 2 Example 3 100 kilos salted calfskins are fulled with 300 liters water and 15 kilos sodium chloride. After the lapse of a day 1 kilo ofa 30% hydrochloric acid is added. After a further 24 hours the hides are removed from the solution and are fulled with 300 liters water" to which have been added 12 kilos of an aqueous solution containing 25% by weight of ammonia and 3 kilos soda. After the lapse of an hour the hairs can be removed.

Example 4 100 kilos salted calfskins are fulled a few hours with 300 liters water, 15 kilos sodium chloride and 1 kilo of a preparation containing pancreas enzymes. 1 kilo of a 30% hydrochloric acid is then added. After 24 hours the acid is neutralized, the hides are removed from the solution and are now fulled with a solution of 12 kilos of av watery'solution containing 25% by weight of ammonia and 3 kilos potash in 300 liters water. I The hides are ready for depilation after one hours. treatment.

Example 5 I 100 kilos salted calfskins are treated during 24 hours with 300 kilos water and 15 kilos sodium chloride, whereupon 1 kilo of a 30% hydrochloric acid is added. After a further 24 hours the hides are placed in a room filled with ammonia vapors. After remaining therein a few hours they are ready for depilation.

Example 6 Example 7 100 kilos salted calfskins are first treated with a mixture of 10 kilos sodium chloride and 1 kilo lactic acid and thereafter-with a mixture of 10 kilos soda, 10 kilos ammonium chloride and 1 kilo of the pancreas enzyme preparation hereinbefore described. The effect is substantially the same as described with reference to the wet treatment.

I wish it to be understood that I do not desire to be limited to the exact substances, proportions and sequence of operations specifically described, as obvious modifications will occur to a person skilled in the art,

I claim 1. The method of treating hides prepara- I tory to tanning, comprising treating the hides first with a solution of a salt of an alkali forming metal and an acid and then with ammoma. I

2. The method of treating hides preparatory to tanning, comprising treating the hides first with a salt of an alkali forming metal and an acid, neutralizing said acid and then treating with ammonia.

3. The method of treating hides preparatory to tanning, comprising treating the hides first with a salt of an alkali forming metal and an'acid and then with ammonia, a tryptically active substance being caused to act on the hide. I

4. The method of treating hides preparatory to tanning,. comprising treating the. hides first with a salt of an alkali forming metal and an acid and then with ammonia,

pancreas enzyme being caused to act on the hide.

5. The method of treating hides preparatory to tanning, comprising treating the hides first with a salt of an: alkali forming metal a and an acid, neutralizing said acid and then treating with ammonia, a tryptically active substance being caused to act on the hide.

6. The method of treating hides preparatory to tanning, comprising treating the hides first with a salt of an alkali forming metal and an acid, neutralizing said acid and 'then treating with ammonia, and causing pancreas enzyme to act on the hide.

7. The'method of treating hides pre aratory to tanning, comprising'treating the ides first with a salt of an alkali forming metal and an acid, neutralizing said acid, rinsing and then treating with ammonia, and causing fiigryptically active" substance to act on'the e. r 8. The method "of treating hides preparatory to tanning, comprising treating the hides first with a sa'lt'of an alkali :forming metal and an acid and-then with ammonia in 'statu nascendi. i :35 9. The method of treating hides preparatory to tanning, comprising treating the hides first with a salt'of an alkali forming metal and an acid and then with ammonia gas. 10. The method of treating hides preparator to tanning, comprising treating the hides first with a salt ofan alkali forming metal and an acid, neutralizing said acid, rinsing and then treating with ammonia and another alkaline compound, and causing pancreas enzyme to act on the hide.

Intestimony whereof I aifix my signature.

o'r'ro-Ro. 

